JPH10119230A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent water resistance and excellent image quality by a method wherein reactive material reacting with polymer is, in an image manner, stuck onto an image forming layer containing polymer provided onto a substrate, and the polymer of a part to which the reactive material is stuck is modified soluble in an eluate. SOLUTION: For an image-forming material, a hydrophobic layer 42 containing polymer having an acidic group as an image forming layer is provided on a hydrophylic substrate 41. A liquid drop containing a basic compound is, in an imaginal manner, stuck to the image forming material by an ink jet method. In a region to which the liquid drop is stuck, a basic compound is reacted with a polymer having the acidic group, and the acid group of the polymer becomes a salt state and modified to be water-soluble. Then, when the image forming material is treated with water, the image forming layer in the region to which the liquid drop is stuck is removed, and the hydrophylic substrate 41 is exposed. Dampening water is stuck to the hydrophylic region to which the liquid drop is stuck, which comes to be water repellent. A hydrophobic region to which the liquid drop is not stuck comes to be ink-acceptive, and the ink is stuck thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording a hydrophilic or hydrophobic image by means of attaching a droplet to an image forming material in accordance with image information such as an ink jet method, The present invention relates to a method for manufacturing a printing plate.

[0002]

2. Description of the Related Art With the development of computer technology, a large amount of information has been digitized and recorded on a magnetic or optical recording medium as digital information. However, the importance of paper as an information recording medium for a long time has not declined at all. Therefore, a computer is essentially required to have a device for outputting digital information to paper, that is, a printer. Various methods have been put into practical use as digital information output devices. The ink jet method developed in recent years is widely used in a simple digital information output device such as a personal computer printer. However, in the ink jet method, there is a limit to the speed at which an image is recorded on one sheet of paper, and the same image cannot be reproduced in large quantities.

The important information that needs to be copied in large quantities is
The method of recording on paper by old printing, especially lithographic printing, is still mainstream even today. In lithographic printing, oil-based ink is used, and ink receiving and ink repelling regions are provided on the surface of the printing plate corresponding to images. Usually, a hydrophilic region and a hydrophobic (ink-receptive) region are provided on the surface of the printing plate, and the hydrophilic region is made ink-repellent by a fountain solution. However, a printing plate (waterless planographic printing plate) using an ink repellent material such as silicone and not using a dampening solution is also practiced. The image recording on the printing plate is performed by exposing the photopolymer photosensitive material (printing original plate) to the image recorded on the silver halide photographic film as a manuscript and eluting the non-image portion to obtain hydrophilicity (ink repellency) or A method of forming an image composed of hydrophobic (ink-receptive) regions is generally used.

When a printing plate is manufactured from digital information, the digital information is output to a silver halide photographic film, and thereafter, the printing plate is manufactured basically in the same manner as in the prior art. Recently, a method of manufacturing a printing plate by directly outputting digital information to a printing original plate has attracted attention as a next-generation technology. Generally CTP (Computer to plate)
Alternatively, it is a technique called DDPP (Digital direct printing plate). Therefore, it has been considered to manufacture a printing plate by using an ink jet method used for a digital information output device. The printing plate first produced by the ink jet method is a waterless lithographic plate using silicone described in JP-A-51-84303. However, waterless lithographic printing plates have the advantage that they can be easily printed, but have problems with the durability (printing durability) of silicone and the quality of the resulting images. The use of an inkjet method has also been proposed in a printing plate manufacturing method using a fountain solution, which is more general than a waterless planographic printing plate. A general method of manufacturing a printing plate (using a fountain solution) by the ink jet method will be described with reference to FIGS. 1 to 3
In the above, a region hatched by a diagonal line rising left means ink repellency or hydrophilicity. The hatched area in the upper right diagonal line indicates ink receptivity or hydrophobicity.

FIG. 1 shows Japanese Patent Application Laid-Open No. 53-15905,
FIG. 4 is a schematic cross-sectional view illustrating a method of manufacturing a printing plate described in each publication of 4-94901. As shown in FIG. 1, a printing plate is manufactured by imagewise directly depositing droplets (12) of a hydrophobic substance on a hydrophilic substrate (11). In printing, the surface of a hydrophilic substrate is made ink-repellent by a fountain solution, and oil-based ink is adhered onto droplets of a hydrophobic substance.

FIG. 2 is a schematic sectional view showing a method of manufacturing a printing plate described in Japanese Patent Application Laid-Open No. 63-102936. As shown in FIG. 2a, a droplet (22) of a photosensitive resin is imagewise deposited on a hydrophilic substrate (21). Next, as shown in FIG. 2B, the printing plate is manufactured by exposing the entire surface (23) and curing the photosensitive resin droplets to form a hydrophobic resin (24). FIG.
FIG. 7 is a schematic cross-sectional view illustrating another method for manufacturing a printing plate described in Japanese Patent Application Laid-Open No. 94901/1994. As shown in FIG. 3A, a photosensitive resin layer (32) is provided on a hydrophilic substrate (31).
Droplets of a coloring substance (3
3) is applied imagewise. Next, as shown in FIG. 3B, when the printing original plate is entirely exposed (34), the droplets (33) of the coloring substance function as a mask, and the photosensitive resin (35) on the portion where the droplets did not adhere is exposed. ) Cures to a hydrophobic resin. Further, as shown in 3c of FIG. 3, the uncured photosensitive resin (and the droplets of the coloring substance) are dissolved in the eluate (3
The printing plate is manufactured by exposing the hydrophilic substrate by removing in step 6). Japanese Patent Application Laid-Open No. 54-94901 discloses a mode in which droplets adhering imagewise function as a mask (resist) for an eluate.
Japanese Patent Application Laid-Open No. 8-52933 describes a method using an ink jet method in producing a printing plate by a silver complex salt diffusion transfer method using a reducing silver compound, a reducing agent and a physical development nucleus. The silver complex salt diffusion transfer method is a very different method from a normal printing plate in that it utilizes the relative hydrophobicity of a silver image.

[0007]

As a method for producing a lithographic printing material using a fountain solution by an ink jet method, various methods have been proposed. However, these methods are easy in image formation (manufacture of a printing plate), but have problems in image durability (printing durability) and image quality. An object of the present invention is to provide a method for easily forming an image having excellent durability and image quality by using a means for attaching a droplet to an image forming material according to image information such as an ink jet method. is there. In particular, it is an object of the present invention to provide a method for directly producing a printing plate from digital image information (DDPP).

[0008]

According to the research of the present inventors,
Reactive substances deposited by the inkjet method have made it possible to change the solubility or the hydrophilicity (or hydrophobicity) of the polymer in the image forming material. The present invention includes the following two aspects (1) and (2) from the viewpoint of the processing step. (1) A reactive substance that reacts with the polymer is adhered imagewise to an image forming layer of an image forming material in which an image forming layer containing a polymer is provided on a substrate. Reacting, thereby denaturing the polymer of the portion to which the reactive substance is attached so as to be soluble in the eluate, and eluting the denatured polymer using the eluate,
An image forming method comprising the step of forming an image comprising the remaining image forming layer. (2) A reactive substance that reacts with the polymer is imagewise attached to the image forming layer of the image forming material in which an image forming layer containing a polymer is provided on a substrate, and the reactive substance and the polymer are combined with each other. Reacting the insoluble polymer in the eluate with the reactive substance attached thereto, and eluting the undenatured polymer using the eluate, thereby leaving the remaining image forming layer. An image forming method, comprising the step of forming an image comprising:

The present invention includes the following three embodiments (a), (b) and (c) from the viewpoint of the material (polymer) used. (A) A basic compound is image-wise adhered onto an image forming layer of an image forming material provided with an image forming layer containing a hydrophobic polymer having an acidic group on a substrate, and the basic compound and the polymer are To make the acidic group of the polymer into a salt state, and to make the polymer of the portion where the basic compound is attached hydrophilic, thereby forming an image comprising a hydrophilic region on the image forming layer. Image forming method. (B) an acidic compound is adhered imagewise on an image forming layer of an image forming material provided with an image forming layer containing a hydrophilic polymer having an acidic group in a salt state on a substrate; Reacting the polymer with the polymer to make the acidic group in a salt state of the polymer into an acid state, and making the polymer of the portion where the acidic compound adheres hydrophobic, thereby forming an image comprising a hydrophobic region in the image forming layer. Forming an image. (C) forming a salt of a polyvalent metal on an image forming layer of an image forming material having an image forming layer containing a hydrophilic polymer having an acidic group in a salt state with a monovalent cation on a substrate; Imagewise, reacting the polyvalent metal ion salt with the polymer to crosslink the polymer and render the polymer of the portion to which the salt is attached hydrophobic, thereby removing the hydrophobic areas from the hydrophobic areas in the image forming layer. An image forming method for forming an image.

The combination of (1) and (a) (1)
The following three embodiments of a), (2b) combining (2) and (b), and (2c) combining (2) and (c) are particularly preferred. (1a) A monovalent basic compound is image-wise adhered onto an image forming layer of an image forming material provided with an image forming layer containing a water-insoluble polymer having an acidic group on a substrate, And the polymer to form a salt with a monovalent cation to convert the acidic group of the polymer to a monovalent cation, whereby the portion of the polymer to which the basic compound is attached is modified to be water-soluble, and modified with water. An image forming method, comprising a step of eluting a polymer and thereby forming an image comprising a remaining image forming layer. (2b) An acidic compound is formed imagewise on an image forming layer of an image forming material in which an image forming layer containing a water-soluble polymer having an acidic group in a salt state with a monovalent cation is provided on a substrate. Adhering, reacting the acidic compound with the polymer to make the acidic group in a salt state of the polymer into an acid state,
This has a step of denaturing the polymer of the portion to which the acidic compound has adhered to water-insoluble, and a step of eluting the undenatured polymer using water and thereby forming an image composed of the remaining image forming layer. Characteristic image forming method.

(2c) A polyvalent metal salt is formed on the image forming layer of an image forming material having an image forming layer containing a water-soluble polymer having an acidic group in a salt state with a monovalent cation on a substrate. Imagewise adhering, reacting the polyvalent metal salt with the polymer to crosslink the polymer, thereby denaturing the polymer in the portion where the salt is attached to water insoluble, and not denaturing with water An image forming method comprising the step of eluting the polymer which has formed and thereby forming an image comprising the remaining image forming layer. In any of the above embodiments, the process of imagewise attaching the reactive substance to the image forming material is preferably performed by an inkjet method. Further, the substrate preferably has a hydrophilic surface. Further, the image composed of the remaining image forming layer is
Preferably it is hydrophobic or ink receptive.

[0012]

As a result of research conducted by the present inventor, it is preferable to employ the processing steps defined in the above (1) or (2) in order to manufacture a printing plate using a fountain solution. found. As a result of further research by the present inventors, it is preferable to use the polymer defined in the above (a), (b) or (c) in order to manufacture a printing plate using a fountain solution. found. As a result of these studies, it has become possible to form an image having excellent image quality and durability (producing a printing plate having excellent image quality and printing durability) by the inkjet method. In the embodiments of the prior art shown in FIGS. 1 and 2, the components corresponding to the image forming layer are attached to the substrate by the ink jet method. Even when the components are adhered to the substrate by the ink jet method, there is a problem in durability (printing durability) of an image (printing plate to be produced) obtained due to insufficient adhesion. In contrast, the method of the present invention forms an image using an image forming material in which an image forming layer is provided on a substrate. By means such as coating, the imaging layer can be firmly deposited on the substrate. Therefore, according to the method of the present invention, an image having excellent durability (a printing plate having excellent printing durability) can be formed.

In the prior art embodiment shown in FIG. 3, the deposited material functions as a mask to form an image. In this method, it is necessary to use a photosensitive composition and carry out overall exposure. According to the method of the present invention, an image (printing plate) can be formed by simple processing without requiring them. As described above, according to the method of the present invention, an image superior to an image obtained by a conventional printing plate manufacturing method by an inkjet method can be manufactured by a simpler method than an ordinary printing plate manufacturing method. Is now possible. In addition,
Generally, in an image forming method, it is desirable that a method of forming a negative image on a document and a method of forming a positive image can be arbitrarily used as needed. In the present invention, the method (1) for forming an image on an exposed portion and the method (2) for forming an image on an unexposed portion are based on the constitution of the image forming material, the type and amount of the material to be used, the solvent of the solution to be adhered. Are basically the same. Therefore, simply changing a part thereof (for example, the difference between whether the acidic group of the polymer in the image forming layer is free or in a salt state,
And the same solutes in the processing solution (basic or acidic substances) and, if necessary, a common image forming process to achieve almost the same physical properties (eg, lipophilicity of the image surface), mechanical strength and image quality. A negative or positive image can be formed. In the conventional image forming method, a method for forming a negative image and a method for forming a positive image have been proposed. Reactions and imaging steps are often different. For this reason, in the prior art, it was difficult to form a homogeneous negative or positive image as in the present invention.

[0014] In a particularly preferred embodiment of the present invention, water can be used as the eluate. In any of the conventional methods requiring an elution treatment, it was necessary to use an alkaline aqueous solution or an organic solvent as an eluent. An alkaline aqueous solution and an organic solvent have a problem in treating waste liquid. If water is used as the eluate (washing liquid), the problem of waste liquid treatment is substantially eliminated. Furthermore, if the image forming material can be eluted with water, the elution step (water washing step) can be omitted. That is, at the beginning of printing, dampening water is attached to a relatively hydrophilic (water-soluble) area, and ink is attached to a relatively hydrophobic area. In this state, the hydrophilicity of the hydrophilic region is insufficient, and the ink gradually adheres to the hydrophilic region to cause stain. However, in the method of the present invention, since the hydrophilic region is water-soluble, the hydrophilic region is gradually eluted by the fountain solution. Eventually (before smearing occurs) printing can be performed with the hydrophilic surface of the substrate exposed and the fountain solution fully functioning (sufficiently repelling the ink). In this way, after writing by the ink jet method, it is also possible to directly print by omitting the washing step (with substantially no processing).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A particularly preferred embodiment of the image forming method of the present invention will be described with reference to FIGS. FIG. 4 shows a preferred embodiment 1a of the image forming method of the present invention.
FIG. 2 is a schematic cross-sectional view of an image forming material used for the present invention. As shown in FIG. 4, a hydrophobic layer (42) containing a polymer having an acidic group is provided on a hydrophilic substrate (41). FIG.
FIG. 1 is a schematic cross-sectional view showing a step of imagewise attaching a basic compound to an image forming material. As shown in FIG. 5, a droplet (51) containing a basic compound is imagewise attached to an image forming material by an ink jet method. FIG. 6 is a schematic cross-sectional view showing the result of the reaction between the basic compound and the polymer.
As shown in FIG. 6, in the area (61) to which the droplet has adhered,
The basic compound reacts with the polymer having an acidic group,
The acidic groups of the polymer are in a salt state. Thereby, the polymer is modified to be water-soluble. On the other hand, in the region (62) where the droplet did not adhere, the polymer did not change.

FIG. 7 is a schematic sectional view showing a removing step using water. As shown in FIG. 7, the image forming material was changed to water (7
When the treatment (washing) is performed in 1), the image forming layer in the area where the droplets adhere is removed, and the hydrophilic substrate is exposed. FIG. 8 is a schematic cross-sectional view showing a state immediately after printing is started without a water removing step. As shown in FIG. 8, dampening water (81) adheres to the hydrophilic region to which the droplet has adhered, and the ink becomes repellent. Then, the hydrophobic area where the droplet has not adhered is ink-receptive, and the ink (82) adheres. FIG. 9 is a schematic cross-sectional view showing a state in which printing is being performed. When printing is started after the water removal step shown in FIG. 7 is performed, as shown in FIG. 9, dampening water (91) adheres to the exposed hydrophilic substrate, and becomes ink repellent. Then, the hydrophobic area where the droplet has not adhered is ink-receptive, and the ink (92) adheres. In addition,
Even if printing is started without the water removing step as shown in FIG. 8, the hydrophilic region to which the droplets are attached is gradually removed by the dampening solution, and the hydrophilic substrate is exposed as shown in FIG. The dampening water comes to adhere there.

FIG. 10 is a schematic sectional view of an image forming material used in another preferred embodiment 2b of the image forming method of the present invention. As shown in FIG. 10, a water-soluble layer (102) containing a polymer having an acidic group in a salt state is provided on a hydrophilic substrate (101). FIG. 11 is a schematic cross-sectional view showing a step of imagewise attaching an acidic compound to an image forming material. As shown in FIG. 11, a droplet (111) containing an acidic compound is imagewise attached to an image forming material by an ink jet method. FIG. 12 is a schematic cross-sectional view showing the result of the reaction between the acidic compound and the polymer. As shown in FIG. 12, in the region (121) where the droplets adhere, the acidic compound reacts with the polymer having an acidic group in a salt state, so that the salt becomes a free acidic group state. Thereby, the polymer is modified to be insoluble in water. In contrast, there is no change in the polymer in the region (122) where the droplet has not adhered.

FIG. 13 is a schematic sectional view showing a removing step using water. As shown in FIG. 13, when the image forming material is treated (washed with water) with water (131), the image forming layer in the area where the droplets did not adhere is removed, exposing the hydrophilic substrate. FIG. 14 is a schematic cross-sectional view showing a state immediately after printing is started without a water removing step. As shown in FIG. 14, dampening solution (14
1) adheres and becomes ink repellent. The hydrophobic area to which the droplet has adhered is ink-receptive, and the ink (142) adheres. FIG. 15 is a schematic sectional view showing a state in which printing is being performed. When printing is started after the water removal step shown in FIG. 13 is performed, as shown in FIG. 15, dampening water (151) adheres to the exposed hydrophilic substrate and becomes ink repellent. The hydrophobic area to which the droplets are attached is ink-receptive, and the ink (15
2) adheres. In addition, even if printing is started without the water removing step as shown in FIG. 14, the hydrophilic region to which the droplets did not adhere is gradually removed by the dampening solution, and the hydrophilic substrate is removed as shown in FIG. Is exposed and dampening water comes to adhere there.

In still another preferred embodiment 2c of the image forming method of the present invention, a printing plate is manufactured and printed in steps similar to those shown in FIGS. That is, the same material as the image forming material shown in FIG.
The salt of a polyvalent metal ion is used in place of the acidic compound shown in (1). As a result, in the region where the droplets adhere, the salt of the polyvalent metal ion reacts with the polymer, and the polymer is crosslinked. Thereby, the polymer is modified to be insoluble in water. In contrast, there is no change in the polymer in the area where the droplet has not adhered. After that, when the treatment is performed in the same manner as in the steps shown in FIGS. 13 to 15, dampening water adheres to the hydrophilic region where the droplet has not adhered, the ink becomes repellent, and the hydrophobic region where the droplet adheres becomes Ink receptive, with ink attached.

[Attachment Means] In the method of the present invention, a reactive substance is imagewise attached to the image forming layer of the image forming material. The reactive substance, whether it is a liquid, a solid, or a powder, can be attached to the image forming layer. However, since the reactive substance needs to react with the polymer in the image forming layer, it is preferable to use a liquid that easily penetrates into the image forming layer. If the reactive substance is a solid,
It can be used as a solution. Alternatively, after the reactive substance is deposited in a solid state, the reactive substance can be diffused into the image forming layer by heating to react with the polymer. As a method of adhering a liquid reactive substance to an image forming material in an image-wise manner, a method of jetting a liquid to the image forming material by an inkjet method, a method of adhering a liquid to an image forming material using a stencil, and a method of applying a liquid There is a method of writing directly on the image forming material by handwriting, and a method of transferring a liquid by bringing another medium having a solution attached thereto into close contact with the image forming material. When digital information is output to an image forming material, an inkjet method is most preferable. When a solid reactive substance is used, the molten or sublimated reactive substance can be imagewise adhered to the image forming layer by a thermal fusion transfer method or a thermal sublimation transfer method. The thermal melting transfer method and the thermal sublimation transfer method
Like the ink jet method, this method is often used in digital information output devices. When a powdery reactive substance is used, the reactive substance can be electrostatically attached to the image forming layer imagewise by electrophotography or electrostatic recording. Electrophotography and electrostatic recording are also commonly used in digital information output devices.

[Substrate] The substrate is paper, synthetic paper, synthetic resin (eg, polyethylene, polypropylene, polystyrene)
Paper, plastic (eg, polyethylene terephthalate, polycarbonate, polyimide, nylon, cellulose triacetate) film, metal plate (eg, aluminum, aluminum alloy, zinc, iron,
It can be made using a copper) plate and paper or plastic film on which these metals are laminated or deposited as a support. Aluminum plate, polyethylene terephthalate film, polycarbonate film,
A composite sheet in which an aluminum sheet is laminated on paper, synthetic paper and polyethylene terephthalate film is preferred. Aluminum plates are particularly preferred. A method for manufacturing an aluminum plate is described in JP-A-8-123035. When the image forming material is used for producing a lithographic printing plate, the surface of the substrate is preferably hydrophilic.
A support having a hydrophilic surface can be used as it is as a substrate. In the case of a support having a hydrophobic surface or insufficient hydrophilicity, such as a polymer film, it is preferable to use a substrate provided with a hydrophilic layer on the support as a substrate. The hydrophilic layer includes a hydrophilic polymer (eg, gelatin,
(Polyvinyl alcohol) as a binder. In the hydrophilic layer, hydrophilic fine particles (eg, silica powder)
Is preferably dispersed.

[Combination of Polymer, Reactive Substance and Eluate] The combination of polymer, reactive substance and eluate in the image forming layer used in the present invention should satisfy the following relationship (1) or (2). Good. (1) When a reactive substance acts on a polymer that is insoluble in an eluate, the polymer becomes soluble in the eluate. (2) When a reactive substance acts on a polymer that is soluble in the eluate, the polymer becomes insoluble in the eluate. In a general polymer chemical reaction, the solubility in a specific liquid often changes. Accordingly, chemical reactions of various types of polymers can be applied to the present invention. The solubility of a polymer in a particular liquid is determined by the molecular weight and chemistry of the polymer. As the molecular weight of the polymer increases, the solubility decreases, and as the molecular weight of the polymer decreases, the solubility increases. Also, as the affinity of the polymer for the liquid increases, the solubility increases, and as the affinity of the polymer for the liquid decreases, the solubility decreases. Therefore, the reactive substance may change the molecular weight of the polymer or the affinity for the liquid.

It is preferred that the side chains (or functional groups) react more than the main chain of the polymer. In order to change the molecular weight of the polymer by the reaction of the main chain, a polymerization reaction or a decomposition reaction of the polymer is required. Side chain (or functional group)
In this case, the molecular weight of the polymer can be significantly changed by a relatively simple crosslinking reaction (or a reaction for cleaving the crosslinking). Also, it is difficult to change the chemical properties of the main chain of the polymer, but the chemical properties of the functional groups can be easily changed. The reaction of the polymer includes an acid-base reaction (details will be described later), an oxidation-reduction reaction (for example, formation or cleavage of a cross-link between polymers by an -S-S- bond), and a hydrolysis reaction (for example, formation of an ester bond in a side chain) Formation of a hydroxyl group or a carboxylic acid group by decomposition), radical crosslinking reaction (for example, attaching a precursor of a radical and crosslinking the polymer by heating or light irradiation), complex formation reaction or polymerization reaction (for example, to a hydrophilic side chain). (Graft polymerization of hydrophobic substances). The reactive substance used in the present invention includes a substance that functions as a catalyst (or an enzyme) in the reaction, in addition to a substance directly involved in the reaction of the polymer.

The reaction of the polymer may be caused to proceed by a treatment such as heating or exposure.
There is a possibility that the effect of the present invention, which can be implemented with simple processing, may be impaired. Therefore, the reaction preferably proceeds at room temperature without requiring external energy. The liquid used as the eluate is neutral water (or aqueous solvent),
Any of an alkaline aqueous solution, an acidic aqueous solution and an organic solvent may be used. However, neutral water (or aqueous solvent)
Is most preferable because it has no problem of waste liquid treatment. Therefore, when the chemical properties of the polymer are changed by the reaction, it is preferable to change the hydrophilic group of the polymer to hydrophobic (reduced solubility in water) or to change the hydrophobic group to hydrophilic. When a polymer having an acidic group or a salt thereof is used, the solubility of the polymer in water can be easily changed by an acid-base reaction. Hereinafter, the polymer having an acidic group will be described in more detail.

[Polymer having acidic group] The polymer having an acidic group is a polymer having an acidic group (eg, a carboxyl group, an acid anhydride group, a sulfonic acid group, a sulfate group, a phosphate group) in a molecule. is there. The molecular weight is 50
It is preferably in the range of 00 to 500,000. The polymer having an acidic group can be synthesized by addition polymerization of a monomer having an ethylenically unsaturated bond. That is, it can be synthesized by homopolymerizing a monomer having an acidic group or copolymerizing with a monomer having no acidic group.
For example, a homopolymer of a vinyl monomer having an acidic group (eg, acrylic acid, methacrylic acid, maleic anhydride, styrenesulfonic acid), or a vinyl monomer having no acidic group with these vinyl monomers (eg, acrylates, Methacrylates, acrylamides,
Methacrylamides, styrenes, vinyl ethers,
(Vinyl esters, ethylene).

Polyester or polyamide can be used as the polymer having an acidic group. Ordinary polyesters or polyamides are synthesized by polycondensation of a divalent or higher valent organic acid with an equimolar amount of a divalent or higher valent alcohol or amine compound. In the synthesis, by using a trivalent or higher acid as a part of the organic acid, a free acidic group can be introduced into the polymer. The polymer having an acidic group can also be synthesized by introducing an acidic group into a natural or synthetic polymer (eg, carboxymethyl cellulose). As the polymer having an acidic group, a polymer which is insoluble in water when the acidic group is in a free acid state (state in which no salt is formed) is used. The properties of such polymers are influenced by the type of acidic groups, the content of acidic groups in the polymer and the degree of hydrophobicity of the polymer backbone. Generally, if the density of the acidic group in 1 g of the polymer is in the range of 5 × 10 ^{−5 to} 3 × 10 ⁻³ mol, the above property is satisfied. In the image forming material of the above-mentioned embodiment (a), a polymer having such an acidic group is used.

In the image forming materials of the above-mentioned embodiments (b) and (c), those in which at least a part of the acidic group of the polymer is neutralized to form a salt, and as a result, the polymer becomes water-soluble are used. The neutralization ratio (the ratio of the acidic groups to salts) required to make the polymer having an acidic group water-soluble depends on the content of the acidic group in the polymer and the nature of the polymer skeleton. It is preferable to select the neutralization rate after confirming the properties. The neutralization ratio is generally preferably in the range of 50 to 100%, and more preferably in the range of 70 to 100%. The acidic group of the polymer used in the image forming material of the embodiment (a) may be a salt as long as the polymer does not become substantially water-soluble.

In order to convert the acidic group of the polymer into a salt, the polymer may be synthesized using a monomer in which the acidic group of the monomer having an acidic group is converted into a salt, or a polymer having an acidic group which is not salted may be synthesized. After synthesizing, the acidic group may be neutralized with a basic substance to form a salt. The cation for converting the acidic group into a salt is preferably a monovalent metal ion or ammonium ion. In the image forming material of the embodiment (c), it is necessary to form a salt with a monovalent cation. Also, in the embodiments (a) and (b), it is preferable to use a monovalent cation (or a monovalent basic compound). Specific examples of the basic compound for neutralizing the acidic group to a salt, lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide,
Sodium carbonate, potassium carbonate, sodium acetate, potassium acetate, sodium silicate, potassium silicate, sodium metasilicate, potassium metasilicate, sodium phosphate, potassium phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, hydroxide Ammonium and organic amines can be mentioned.

[Image forming layer] The image forming layer is a layer containing the above-mentioned polymer as a main component. A colorant can be added to the image forming layer for the purpose of visualizing an image.
Known pigments or dyes can be used as the colorant. A surfactant can be added to the image forming layer. As the surfactant, a known nonionic activator, anionic activator, cationic activator, amphoteric activator or fluorine-containing activator can be used.

The image-forming layer may contain a polymer having no acidic group in addition to the polymer having an acidic group (or a salt thereof), as long as the solubility is not impaired. Examples of polymers having no acidic group include vinyl polymers (eg, polyacrylates, polymethacrylates), synthetic polymers such as polyesters and polyamides, and natural or semi-synthetic polymers such as celluloses. be able to.

When the obtained image is used as a lithographic printing plate, the surface of the image portion must be lipophilic to some extent because the image portion needs to receive (flood) the printing ink. When the lipophilicity of the polymer having an acidic group is insufficient, as long as the solubility is not impaired,
An oily substance can be added to the image forming layer for the purpose of improving the inking property of the image area. Examples of the oily substance include polymer plasticizers (eg, phthalates, phosphates), higher fatty acid esters (eg, linseed oil, poppy oil), paraffins, and waxes.

The thickness of the image forming layer is 0.3 to 30 μm
, And more preferably in the range of 0.5 to 5 μm.

[Overcoat layer] An overcoat layer can be provided on the image forming layer. The overcoat layer is preferably made of a water-soluble polymer. With the overcoat layer, it is possible to adjust the wettability, penetrability (absorbency), bleeding property, and image quality of the droplets ejected by the inkjet onto the image forming material. Further, when the overcoat layer is present, the dissolution of the non-image portion into water may increase. Examples of water-soluble polymers include polyvinyl alcohol (including modified polyvinyl alcohol), polyvinyl pyrrolidone, sodium poly (meth) acrylate, poly (meth) acrylamide, sodium polystyrene sulfonate, methyl cellulose, hydroxypropyl cellulose, and sodium carboxymethyl cellulose. Salts, gelatin and acacia can be mentioned. The overcoat layer can contain the same surfactant as that used for the image forming layer. The overcoat layer can include a matting agent. By adding the matting agent, the overcoat layer becomes porous, and the wettability and the permeability of the droplets ejected by the ink jet to the image forming material can be adjusted. The matting agent also has the effect of reducing the tackiness of the surface of the image forming material and preventing adhesion when the image forming materials are stacked. The matting agent is preferably an inorganic or organic solid powder. Examples of matting agents include silicon dioxide, zinc oxide, titanium dioxide, alkaline earth metal salts, clays, natural polymers (eg, starch, cellulose) and synthetic polymers. The thickness of the overcoat layer is preferably in the range of 0.1 to 10 μm.

[Image Forming Step] Each step of the image forming method will be described in more detail by taking the embodiments (1a), (2b) and (2c) as examples. In a particularly preferred embodiment of the present invention, a solution of a reactive substance is imagewise attached to the image forming material by an ink jet method, and then washed with water to elute and remove a water-soluble portion (non-image portion) of the image forming layer from the support. It is done by doing.

In the image forming method of the embodiment (1a), it is preferable to attach a solution of a basic compound to the image forming layer. The basic compound is preferably monovalent. Specific examples of the basic compound include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium carbonate, potassium carbonate, sodium acetate, potassium acetate, sodium silicate, potassium silicate, and metasilicate. Examples include sodium, potassium metasilicate, sodium phosphate, potassium phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, ammonium hydroxide and organic amines. The concentration of the basic compound in the solution is preferably in the range of 0.03 to 5 mol / l, more preferably in the range of 0.1 to 2 mol / l.

In the image forming method of the embodiment (2b), it is preferable that a solution of an acidic compound is adhered to the image forming layer. As the acidic compound, any of inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid and organic acids such as acetic acid, oxalic acid, citric acid and benzenesulfonic acid can be used. The concentration of the acidic compound in the solution is preferably in the range of 0.03 to 5 mol / l,
More preferably, it is in the range of 1 to 2 mol / l.

In the image forming method of the embodiment (2c), it is preferable that a solution of a polyvalent metal ion salt is adhered to the image forming layer. Examples of polyvalent metal ion salts include divalent metals (preferably alkaline earth metals) such as magnesium, calcium, strontium, barium, aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, and tin. Salts (including complex salts) of the above cations can be mentioned. The counter anion may be any,
It is preferable to select an anion having good solubility of the metal salt.
Specific examples of polyvalent metal ion salts include magnesium chloride,
Examples thereof include magnesium sulfate, magnesium nitrate, magnesium acetate, calcium chloride, calcium sulfate, calcium nitrate, and calcium acetate. The concentration of the polyvalent metal ion salt in the solution is preferably in the range of 0.03 to 5 mol / l, and more preferably in the range of 0.1 to 2 mol / l. In addition, even if the acidic group of the polymer having an acidic group is in the form of a salt, the cation can be substituted with the above-mentioned polyvalent metal ion, and the polymer can be crosslinked to be modified to be water-insoluble.

The solvent used in the above solution is the same as in the embodiment (1a)
In any of the cases (2) to (2c), it is preferable that water is the main component. Various characteristics of the ink jet method (particle size of droplets, driving frequency, or wettability, penetrability, and bleeding of the droplets to the image forming material) are factors that affect the recording speed and image quality. These properties are generally affected by physical properties such as surface tension and viscosity of the solution. For the purpose of adjusting these physical properties, an organic solvent, a surfactant and a thickener that can be mixed with water can be added to the solution of the reactive substance. As the thickener, a water-soluble polymer used in the above-mentioned overcoat layer is preferable. The solution of the reactive substance may be colored with a coloring agent.

When the image forming method of the present invention is used for producing a printing plate, the water elution treatment of the non-image area can be omitted. In other words, after writing with inkjet, if you start printing directly on the printing press without a water elution process, the non-image part is eluted on the printing press by the dampening water, and then the water is eluted and then the printing plate is printed Printing can be performed in the same manner as when the printer is mounted on a printer. When the overcoat layer does not exist, printing can be performed before the non-image portion is eluted with the dampening solution. That is, the printing ink immediately starts to be applied to the image portion. Although a water-soluble polymer (a polymer in which an acidic group has been converted into a salt) remains in the non-image portion, since the ink is highly hydrophilic and hardly adheres to the oil-based ink, background contamination is less likely to occur.
Before the background stain starts to appear, the non-image area is eluted with the fountain solution to expose the hydrophilic (ink repellent) support surface. Therefore, the printing performance (the number of waste sheets and the ink density) is essentially the same as the case where printing is started by using a printing machine after elution with water. On the other hand, when the overcoat layer is present, the image portion is covered with the hydrophilic overcoat layer, so that the ink does not adhere thereto, and the overcoat layer is eluted with the dampening water, so that printing can be performed. The number of broke sheets is determined by the dissolution rate of the overcoat layer. In the non-image area, as in the case where the above-mentioned overcoat layer does not exist, no background stain occurs.

After the water elution treatment, the obtained image can be heated for the purpose of increasing the mechanical strength of the image, and particularly improving the printing durability when the image is used as a printing plate. Heating can be performed by a method of closely contacting a heated object, a method of irradiating infrared rays, or the like. The heating temperature is preferably in the range of 80 to 300 ° C, and 100 to 2
The temperature is more preferably in the range of 00 ° C. The heating time is preferably from 10 seconds to 10 minutes, more preferably from 20 seconds to 3 minutes.

[Applications] The image forming method of the present invention is applicable to hard copy, slides for overhead projectors,
It can be used for the production of indoor and outdoor display objects (bulletin boards, posters, signs, design crafts, arts). Particularly, when it is necessary to duplicate a large number of images obtained by outputting digital information, the image forming method of the present invention can create a printing plate using a digital information output device such as an ink jet method. Therefore, it is particularly effective. According to the method of the present invention, a printing plate can be produced directly from electronic image information using an inexpensive material and with a simple treatment or no treatment that does not generate a harmful alkali treatment waste liquid.

[0042]

【Example】

[Example 1] (Preparation of image forming material) "Preparation of aluminum substrate" JIS having a thickness of 0.24 mm
The surface of the aluminum plate according to -A-1050 was grained with a nylon brush and an aqueous suspension of pamistone (400 mesh), and then thoroughly washed with water. Next, the film was immersed in a 10% aqueous solution of sodium hydroxide at 70 ° C. for 60 seconds for etching, washed with running water, neutralized and washed with a 20% aqueous solution of nitric acid, and then washed with water. The obtained aluminum plate was subjected to a rectangular alternating current (anode voltage: 1.27).
v, the ratio of the quantity of electricity at the cathode to the quantity of electricity at the anode: 0.9,
Amount of electricity at anode: 160 coulomb / dm ² )
The electrolytic surface roughening treatment was performed in a 1% nitric acid aqueous solution containing 0.5% aluminum nitrate. The surface roughness of the obtained plate was 0.6 μm (Ra indication). Following this treatment, the substrate was immersed in a 1% aqueous sodium hydroxide solution at 40 ° C. for 30 minutes, and then treated in a 30% aqueous sulfuric acid solution at 55 ° C. for 1 minute. Next, in a 20% sulfuric acid aqueous solution, the thickness is 2.5 g.
/ Dm ² , the current density is 2
Anodizing treatment was performed under the condition of A / dm ² , washing with water, and drying, to produce an aluminum substrate.

"Formation of Image Forming Layer" The following coating solution was applied on the above aluminum substrate and dried to form a film having a thickness of 2.
An image forming layer having a thickness of 0 μm was provided.

────────────────────────────────────Coating solution for image forming layer────── ────────────────────────────── Methyl methacrylate / methacrylic acid copolymer (copolymerization ratio = 70/30) 0.6 g propylene glycol Monomethyl ether 3.0 g Methyl ethyl ketone 3.0 g Copper phthalocyanine 0.1 g

(Image formation) The ink in the ink container of a commercially available ink jet printer was replaced with the following solution, and the solution was attached to the image forming material according to the character information from a personal computer.

溶液 Solution ────────── ０．４ 0.4N sodium hydroxide aqueous solution 10.0g sodium dodecylbenzenesulfonate 0.001g ────── ──────────────────────────────

After that, when the image forming material was washed with water, the character portion to which the above solution adhered was eluted with water to expose the aluminum substrate, and the portion to which the solution did not adhere remained on the aluminum substrate to form a clear image. Been formed. When printing was performed using this image as a printing plate, a good printed matter was obtained.

Example 2 (Preparation of Image Forming Material) "Formation of Image Forming Layer" A 4% by weight solution of sodium hydroxide in methanol was prepared while stirring a solution having the following composition.
7 g were added. This solution was applied on the aluminum substrate of Example 1 and dried to form an image forming layer having a thickness of 2.0 μm.

<< Composition Liquid for Image Forming Layer >> ─────────────────────────────── Methyl methacrylate / methacrylic acid copolymer (copolymerization ratio = 70/30) 0.6 g propylene Glycol monomethyl ether 3.0 g Methyl ethyl ketone 3.0 g Copper phthalocyanine 0.1 g ─

(Image formation) The ink in the ink container of a commercially available ink jet printer was replaced with the following solution, and the solution was attached to the image forming material according to the character information from a personal computer.

溶液 Solution ────────── ────────────────────────── 0.4N hydrochloric acid aqueous solution 10.0g sodium dodecylbenzenesulfonate 0.001g ──────── ────────────────────────────

After that, when the image forming material was washed with water, the portion where the above solution was not adhered was eluted with water to expose the aluminum substrate, and the character portion where the solution was adhered remained on the aluminum substrate to form a clear image. Been formed. When printing was performed using this image as a printing plate, a good printed matter was obtained.

Example 3 (Preparation of image forming material) An image forming material was prepared in the same manner as in Example 2.

(Image formation) The ink in the ink container of a commercially available ink jet printer was replaced with the following solution, and the solution was attached to the image forming material according to the character information from a personal computer.

溶液 Solution ──────────水溶液 4.4% by weight aqueous solution of calcium chloride 10.0 g Sodium dodecylbenzenesulfonate 0.001 g ──── ────────────────────────────────

After that, when the image forming material was washed with water, the portion where the above solution was not adhered was eluted with water to expose the aluminum substrate, and the character portion where the solution was adhered remained on the aluminum substrate to form a clear image. Been formed. When printing was performed using this image as a printing plate, a good printed matter was obtained.

Example 4 (Preparation of Image Forming Material) In the same manner as in Example 2, an image forming layer was provided on an aluminum substrate, and the following coating solution was applied thereon and dried. A 0.5 μm overcoat layer was provided.

塗布 Coating solution for overcoat layer──────ポ リ ビ ニ ル Polyvinyl alcohol 1.0 g Sodium dodecylbenzenesulfonate 0.01 g Water 10.0 g ─── ─────────────────────────────────

(Image formation) As a result of forming an image in the same manner as in Example 2, the same clear image and printed matter as in Example 2 were obtained.

Example 5 Using the image forming material of Example 2, a solution was applied to the image forming material by the ink jet method in the same manner as in Example 2. Thereafter, the image forming material was directly mounted on a printing machine without washing with water, and printing was performed using a fountain solution. Printing was performed in the same manner as in the case of printing in Example 2, and the number of waste sheets did not increase.

Example 6 The thickness of the support was 50 μm.
An image forming material was prepared by providing an image forming layer in the same manner as in Example 2 using the above polyethylene terephthalate film. The solution was deposited on the image forming material by the ink jet method in the same manner as in Example 2 and washed with water.
HP slides were obtained.

[Brief description of the drawings]

FIG. 1 shows JP-A-53-15905 and JP-A-54-9490.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view illustrating a method of manufacturing a printing plate described in each of the publications.

FIG. 2 is a schematic cross-sectional view showing a method of manufacturing a printing plate described in JP-A-63-102936.

FIG. 3 is a schematic cross-sectional view showing another method of manufacturing a printing plate described in JP-A-54-94901.

FIG. 4 is a schematic cross-sectional view of an image forming material used in a preferred embodiment 1a of the image forming method of the present invention.

5 is a schematic cross-sectional view showing a step of imagewise attaching a basic compound to the image forming material shown in FIG.

6 is a schematic cross-sectional view showing a result of a reaction between a basic compound and a polymer in the image forming material shown in FIG.

FIG. 7 is a schematic sectional view showing a step of removing the image forming material shown in FIG. 4 with water.

FIG. 8 is a schematic cross-sectional view showing a state immediately after printing is started without removing the image forming material shown in FIG. 4 using water.

9 is a schematic cross-sectional view showing a state where printing is performed on the image forming material shown in FIG.

FIG. 10 shows another preferred embodiment 2 of the image forming method of the present invention.
FIG. 4 is a schematic cross-sectional view of an image forming material used in FIG.

11 is a schematic cross-sectional view showing a step of imagewise attaching an acidic compound to the image forming material shown in FIG.

12 is a schematic cross-sectional view showing a result of a reaction between an acidic compound and a polymer in the image forming material shown in FIG.

FIG. 13 is a schematic cross-sectional view showing a step of removing the image forming material shown in FIG. 10 with water.

FIG. 14 is a schematic cross-sectional view showing a state immediately after printing is started without removing the image forming material shown in FIG. 10 using water.

FIG. 15 is a schematic cross-sectional view showing a state where printing is being performed on the image forming material shown in FIG. 10;

[Explanation of symbols]

11, 21, 31, 41, 101 hydrophilic substrate 12 droplet of hydrophobic substance 22 droplet of photosensitive resin 23, 34 light 24, 35 hydrophobic resin 32 photosensitive resin layer 33 droplet of coloring substance 36 eluent 42 Hydrophobic layer containing polymer having acidic group 51 Droplet containing basic compound 61, 121 Region to which droplet is attached 62, 122 Region to which droplet is not attached 71, 131 Water 81, 91, 141, 151 Dampening solution 82, 92, 142, 152 ink 102 water-soluble layer 111 containing a polymer having an acidic group in a salt state 111 droplets containing an acidic compound

Claims (5)

[Claims] A reactive substance reacting with a polymer is imagewise deposited on an image forming layer of an image forming material provided with an image forming layer containing a polymer on a substrate. Reacting the polymer with the polymer, thereby denaturing the polymer in a portion to which the reactive substance has adhered so as to be soluble in the eluate, and eluting the denatured polymer using the eluate, and thereby remaining the image forming layer. An image forming method, comprising the step of forming an image comprising: 2. A basic compound is adhered imagewise on an image forming layer of an image forming material in which an image forming layer containing a hydrophobic polymer having an acidic group is provided on a substrate. By reacting the polymer with the polymer to make the acidic group of the polymer into a salt state, and making the polymer of the portion where the basic compound adheres hydrophilic, thereby forming an image comprising a hydrophilic region in the image forming layer. Characteristic image forming method. 3. A reactive substance which reacts with the polymer is imagewise deposited on an image forming layer of an image forming material in which an image forming layer containing a polymer is provided on a substrate. A step of reacting the polymer with the polymer and thereby denaturing the polymer in a portion to which the reactive substance has adhered so as to be insoluble in the eluate, and eluting the non-denatured polymer using the eluate, thereby remaining image An image forming method, comprising a step of forming an image comprising a forming layer. 4. An acidic compound is image-wise adhered on an image forming layer of an image forming material provided with an image forming layer containing a hydrophilic polymer having an acidic group in a salt state on a substrate. The acidic compound is reacted with the polymer to make the acidic group in a salt state of the polymer into an acid state, and the polymer in a portion where the acidic compound is adhered is made hydrophobic, whereby the image forming layer is removed from the hydrophobic region. An image forming method for forming an image. 5. An image forming material comprising an image forming layer comprising a hydrophilic polymer having an acidic group in the form of a salt with a monovalent cation on a substrate. The salt is imagewise deposited, the salt of the polyvalent metal ion is reacted with the polymer to crosslink the polymer, and the portion of the polymer to which the salt of the polyvalent metal ion is attached is made hydrophobic, thereby forming an image. An image forming method comprising forming an image comprising a hydrophobic region in a layer.